Ecotoxicology (2016) 25, 655-663

Youhui Gong, Xueyan Shi, Nicolas Desneux and Xiwu Gao (2016)
Effects of spirotetramat treatments on fecundity and carboxylesterase expression of Aphis gossypii Glover
Ecotoxicology 25 (4), 655-663
Abstract: Spirotetramat is a novel tetramic acid-based insecticide, belonging to keto-enol pesticide family, with a novel mode of action; it interferes with lipid biosynthesis. Its insecticide activity against various agricultural pest insects have been demonstrated (e.g. on Myzus persicae, Bemisia tabaci and Tetranychus urticae). However, information available is currently limited on the efficacy of spirotetramat on the cotton aphid, Aphis gossypii, a key cotton pest worldwide. We assessed the spirotetramat toxicity on A. gossypii and evaluated its effects on aphid fecundity when exposed to a sublethal concentration (LC₁₀) and to increasing lethal concentrations (LC₂₅, LC₅₀, and LC₇₅). A key mechanism involved in insecticide resistance in aphids relates to esterase activity. We estimated the CarE activity and a CarE gene expression in aphids in response to spirotetramat exposure, then we tested tolerance of offspring to spirotetramat when the parents were exposed to the highest concentration tested in our study (LC₇₅). Results showed that spirotetramat showed increasing toxicity to A. gossypii with exposure duration to treated leaves; LC₅₀ ranged from 23,675.68 to 12.27 mg/L for 1 to 5-days exposure. In addition, spirotetramat reduced aphid daily fecundity, in all concentration treatments, especially with up to 90 % reduction in case of exposure to LC₇₅. Total CarE activity increased dramatically and CarE mRNA expression was also up regulated in aphids after exposure to LC₇₅ spirotetramat. Finally, the tolerance to spirotetramat in offspring (when parents were exposed to the LC₇₅) showed a 2.5-fold increase when compared to control aphids. Consequently, spiroteramat showed potential for pest management of cotton aphids owing to both lethal and sublethal activities, notably strong impact on aphid fecundity. However, we also demonstrated that increased tolerance of A. gossypii to spirotetramat may happen through increased CarE- activity and subsequent metabolic degradation of the insecticide in aphids' body.
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Link to article at publishers website
Database assignments for author(s): Xi-Wu Gao, Nicolas Desneux, Youhui Gong

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Aphis gossypii